1. Field of the Invention
This present invention relates to a method for activating a semiconductor structure, and more particularly to a method for activating a P-type semiconductor layer of a semiconductor structure.
2. Description of the Prior Art
In recent years, The Light-Emitting Diode (LED) has become more and more popular. However, a blue light-emitting device employing a blue color-emitting element has not yet been developed as a practical device. Actually, P-type III-V Group compound semiconductor having a sufficiently low-resistance cannot be produced by any conventional techniques. In the case of a GaN series compound semiconductor, as an active layer of an LED, there is a tendency for the semiconductor to exhibit n-type characteristics even without doping an n-type impurity. Therefore, some P-type dopants, such as Mg or Zn, are doped into the GaN series compound semiconductor. Even by conventional chemical vapor deposition or any like method while doping P-type impurities, it is impossible to make III-V Group compound semiconductor characteristic P-type. That is because an activating process is necessary after developing the III-V Group compound semiconductor.
In the prior art, one well-known method for activating the active layer is heating the LED structure with a furnace or through a rapid thermal annealing process. The above-mentioned method sends the substrate with the active layer thereon into a high temperature furnace, to activate the active layer. The substrate with the active layer thereon is heated under a temperature about hundreds of degree C. According to the above-mentioned method, the active layer can be activated under the high temperature, but the other portion of the LED may be hurt under the temperature.
Another well-known method for activating the active layer is irradiating electron beams on the active layer. According to this method, the uppermost active layer is activated by irradiating electron beams while maintaining a surface temperature of the active layer at 600° C. or higher. However, this method still activates the active layer by heat. Moreover, the above-mentioned method is rarely applied on manufacturing process, because the method cannot be easily applied on a wide semiconductor device.
Hence, it is an important object, in developing a method for activating the active layer of a semiconductor device without thermal effects to lower the resistance of a semiconductor device and optimize the performance of the semiconductor device.